1. Field of the Invention
The present invention generally relates to equipment used in oil and gas wells after drilling is completed and more particularly to a gauge carrier which is tubing conveyed with wireline retrievable gauges or gauge assembly for more effectively evaluating reservoir potential and whether it is economically feasible to complete the well and place it into production. The gauge carrier of this invention provides effective solutions to problems which arise when endeavoring to measure and accurately record bottom hole pressure during temporary flow tests as well as on a permanent hookup on a well completion. The gauge carrier can be run on the tubing or drillstem above or below a packer as a part of a temporary or permanent completion and the gauge assembly can be retrieved by the use of a wireline after the well completion process has been completed. The gauge carrier provides a support structure for mechanical or electronic gauges utilizing components which are readily available or easily constructed to enable the measuring gauges to be retracted, checked and easily run back into the bore hole if additional information is required at any time during flowing and/or shut-in conditions.
2. Information Disclosure Statement
It is well-known practice for oil and gas well service companies to gauge well performance with the existing method or practice involving a cage that may be integral with the drill string being lowered into the well with the drill string with the cage carrying a plurality of units for measurement and recording of conditions at the bottom of the bore hole with this information then being used to determine whether the well is to be placed into production. This known technique, which is usually referred to as drillstem testing which basically involves the use of well-known downhole equipment which can be manipulated from the surface to accomplish basic functions by following certain procedural steps. The basic equipment used is a string of tubing o drill pipe which is also known as a test string which extends from the surface to a predetermined depth within the well casing thereby providing control of the underground environment with the casing containing the drilling mud that was used to drill the well and to control and contain any reservoir fluids encountered.
The lower end of the test string is provided with a packer which can be set against the wall of the casing and released as required to prevent reservoir fluids from entering the casing in order to keep the well under control after the reservoir has been perforated. In order to further perforate and evaluate the reservoir, a gauge carrier is usually affixed to the drill string beneath the packer with the gauge carrier having pressure recording gauges and the like affixed in recesses or receptacles machined into the exterior of a heavy wall pipe in order to prevent the gauges from contacting the wall of the casing which could result in damage to the gauges. A perforating gun can be positioned below the gauge carrier and affixed to the gauge carrier with the perforating gun being conveyed by tubing. The perforating gun is normally actuated by dropping a rod of sufficient length and weight to cause the explosive charge within the perforating gun to perforate the casing and allow the reservoir fluids to enter the casing and pass upwardly through the gauge carrier to the surface in order for measurement data to be obtained. Thus, the pressure recording gauges measure bottom hole pressure, temperatures and other conditions while the well is flowing or while the well is shut-in.
While this arrangement for gathering downhole pressure and other data has been used, it has some shortcomings. Inasmuch as the pressure recording gauges have to be run in the hole with the test string, the gauges must be programmed prior to being run into the hole. Also, the gauges undergo violent shocks when run in the hole in conjunction with tubing conveyed perforating guns thus requiring service companies and operators to run multiple gauges in order to assure accurate and proper data gathering with it being common practice to run four, six and sometimes eight gauges at one time to assure data recording. Further, in the known arrangement, the pressure recording gauges cannot be retrieved without killing the well and going through the tedious process of removing the test string from the well.